Combined Pore Network and Finite Volume Modelling of Water Movement in PEM Fuel Cell Porous Transport Layers

The effects of water transport in the porous transport layers (PTLs) of polymer electrolyte membrane (PEM) fuel cells are commonly studied using sub-scale pore network models or geometric models which generate effective properties that can be applied in computational fluid dynamics (CFD) models using a continuum approach at larger length scales. This approach is commonly uncoupled and uses a steady state approach, thereby approximating and averaging important details of water transport effects. To capture water transport in sub-scale CFD models requires extensive computer resources and is often very difficult to converge.  In this work, a three-dimensional pore network model is implemented in the open-source, finite-volume CFD code, OpenFOAM. The model captures transient water transport through a network of pores using an experimentally determined pore size distribution. This model is directly coupled to a continuum model to directly capture the effect of liquid water on fuel cell performance.  After a description of the method, results are compared with those from an in-house pore-network model for code verification. The method presents a novel approach which benefits from both pore-network modelling and CFD to investigate the subject of water transport in PEM fuel cells.